Wireless energy transfer system based on 3D wearable litz double coils

Abstract

Over the last decade, people paid a lot of attention to wireless magnetic resonant energy transfer system. It has become one of best method to supply power for implantable electronic devices. In this paper, a 3D wearable litz double coils (3D-WLDC) with two identical integrated flexible coils is proposed and the corresponding theoretical model for inductance, AC resistance, and quality factor is built up. Based on the theoretical model, 3D-WLDC with different numbers of strands and turns are designed to study the effects of geometric parameters on the coil performance. Several 3D-WLDCs with different numbers of strands and turns are wound and measured by impedance analyzer to validate the proposed theoretical model. The measured results of the 3D-WLDC are in agreement with the theoretical model. Two similar 3D-WLDCs, each with 6 mm diameter, are wound around an implantable capsule and applied to set up the wireless energy transfer system, which can greatly save the volume of implantable electronic devices. The no-load power transfer efficiency is 33.77 % at the working frequency of 13.56 MHz, when the transmission distance is 5 mm. A power of 21.82 mW is received when the load resistance is 100 Ω.